Down hole method for determination of formation properties

Abstract

The apparatus of the present invention relates to a down hole tool capable of extraction of valid samples and making pressure measurements useful in calculating formation permeability. The tool incorporates the features of a straddle packer to allow formation fluid specimens to be taken at large flow rates without depressing the pressure below the formation fluid bubble point. When used in combination with a pressure probe the tool is used to obtain meaningful permeability readings in a larger radius area than previously permitted with known designs. Additionally, the apparatus of the present invention allows flow control during the creation of the pressure pulse which enhances extraction of valid samples and the permeability determination. The apparatus may be modularly constructed so that in a single descent of the tool, a pressure profile of the zone of interest can be made, a fluid analysis can be made at each station, multiple uncontaminated fluid samples can be withdrawn at pressures above the bubble point, local vertical and horizontal permeability measurements can be made at each station, a packer module can be set at a location dictated by previous measurements and a large scale pressure build up test can be performed.

We claim: 
     
       1. A multi purpose downhole method for obtaining data regarding formation fluid properties by means of a downhole tool comprising: formation fluid pulsing by means having an inlet positioned to provide fluid communication between the formation fluids and the interior of the tool for selectively creating a pressure transient in the formation fluid zone;   sealing off a segment of the bore hole from well fluids located above and below said inlet by packer means mounted above and below said inlet; and   detecting a formation pressure transient created by said pulsing means.   
     
     
       2. The method of claim 1 wherein said fluid pulsing step further comprises: establishing a flow line between the formation and the tool including a flow sensing element; and   selectively adjusting a restriction device mounted in said flow line to regulate the fluid flow rate.   
     
     
       3. The method of claim 2 wherein said formation fluid pulsing step further comprises: establishing a first fluid communication with said flow line, and extending to the outer surface of said tool; and   establishing a second fluid communication extending longitudinally through the length of a sample chamber module and in selective fluid communication with said flow line and said first fluid communication.   
     
     
       4. The method of claim 3 further comprising: measuring physical properties of the formation fluid by fluid analysis means;   measuring formation fluid pressure by pressure measurement means;   establishing a third fluid communication between said second fluid communication and said fluid analysis means and said precision pressure measurement means; and   selectively pumping fluid in all of said flow lines into and out of said tool.   
     
     
       5. A multi purpose downhole method for obtaining data regarding formation properties by means of a downhole tool comprising the steps of: formation fluid pulsing by means having an inlet positioned to provide fluid communication between the formation fluids and the interior of the tool for selectively creating a pressure transient in the formation fluid zone;   regulating the fluid flow rate between the formation fluid and the tool in a manner as to prevent reduction of pressure of formation fluid flowing into said inlet, below its bubble point; and   detecting a formation pressure transient created by said pulsing means.   
     
     
       6. The method of claim 5 wherein said fluid flow regulating step further comprises: establishing a flow line between the formation and the tool including a flow sensing element and a selectively adjustable restriction device mounted in the flow line; and   selectively adjusting said restriction device to regulate the fluid flow rate.   
     
     
       7. The method of claim 5 further comprising the steps of: measuring physical properties of the formation fluid;   measuring the formation fluid pressure; and   selectively pumping fluid out of the interior of said tool.